Search

Low–molecular mass protein 7 (LMP7) is a proteolytic subunit of the immunoproteasome that is involved in regulating inflammatory responses. However, the role of LMP7 in the pathogenesis of abdominal aortic aneurysm (AAA) remains unknown. In this study, ApoE knockout (KO) or LMP7/ApoE double KO (dKO) mice were infused with angiotensin II (Ang II, 1000 ng/kg per minute) for up to 28 d. We found that LMP7 expression was significantly upregulated in AAA tissues from ApoE KO mice and human patients. Moreover, Ang II infusion markedly increased the incidence and severity of AAA in ApoE KO mice, which was considerably reduced in LMP7/ApoE dKO mice. Histological alterations, including aortic wall thickening, collagen deposition, elastin fragmentation, and vascular smooth muscle cell apoptosis in AAA tissue of ApoE KO mice, were also significantly attenuated in LMP7/ApoE dKO mice. Interestingly, LMP7/ApoE dKO mice showed a marked reduction of infiltration of CD3+ T cells, especially CD4+ T cells in AAA tissues compared with ApoE KO mice. Moreover, ablation of LMP7 substantially inhibited the differentiation of CD4+ T cells into Th1 and Th17 cells by reducing the activation of multiple transcriptional factors. We also investigated the effects of an LMP7-specific inhibitor PR-957 (also known as ONX 0914) on AAA formation in ApoE KO mice. PR-957 treatment could reduce the AAA incidence and severity. In conclusion, our results provide, to our knowledge, novel evidence that ablation or pharmacological inhibition of LMP7 attenuates Ang II–induced AAA formation, and LMP7 might be a novel therapeutic target for treating AAA in humans.

Background/Aims: GLP-1 and ghrelin are common appetite-regulating hormones. Both have multiple functions beyond metabolic regulation. However, the effects of GLP-1 and ghrelin on endothelial biology are not fully understood. Here, we investigate the roles of GLP-1 and ghrelin in microvascular endothelial apoptosis and senescence. Methods: Human microvascular endothelial cells (HMECs) were exposed to high glucose/high lipid (HG/HL) conditions and treated with GLP-1 or ghrelin. Cellular apoptosis, senescence, and mitochondrial function were measured. In addition, the MAPK and Akt signaling pathways were examined. Results: Both GLP-1 and ghrelin treatment decreased the number of TUNEL-positive cells and inhibited caspase-3 and PARP cleavage and mitochondrial dysfunction in HG/HL-exposed HMECs. GLP-1, but not ghrelin decreased the number of β-galactosidase (β-gal)-positive cells. Furthermore, GLP-1 and ghrelin inhibited ERK1/2, JNK1/2, and p38 signaling. GLP-1 suppressed Akt signaling, but ghrelin had no effect. Moreover, JNK1/2 and p38 inhibitors, but not ERK1/2 and Akt inhibitors, decreased the number of TUNEL-positive cells. Additionally, only the Akt inhibitor decreased the number of β-gal-positive cells. Conclusion: These results demonstrate that GLP-1 and ghrelin inhibit mitochondrial dysfunction under HG/HL conditions, and suppress endothelial apoptosis via inhibiting JNK1/2 and p38 signaling; moreover, GLP-1 alleviates endothelial senescence via inactivating Akt signaling.